Alphaviruses are enveloped RNA viruses that contain several human pathogens. Due to intrinsic heterogeneity of alphavirus particles, a high resolution structure of the virion is currently lacking. Here we provide a 3.5 Å cryo-EM structure of Sindbis virus, using block based reconstruction method that overcomes the heterogeneity problem. Our structural analysis identifies a number of conserved residues that play pivotal roles in the virus life cycle. We identify a hydrophobic pocket in the subdomain D of E2 protein that is stabilized by an unknown pocket factor near the viral membrane. Residues in the pocket are conserved in different alphaviruses. The pocket strengthens the interactions of the E1/E2 heterodimer and may facilitate virus assembly. Our study provides structural insights into alphaviruses that may inform the design of drugs and vaccines.

Stem cell–based bone tissue engineering has been recognized as a new strategy for maxillary sinus floor elevation. More rapid bone formation may enhance this technique when simultaneous dental implant placement is desired. Adipose tissue–derived stem cells (ADSCs) and bone marrow stem cells (BMSCs) are the most well-characterized cell sources for bone regeneration, but comparative studies on the osteogenic potential of these cells have yielded conflicting conclusions. This study aimed to compare the rapid bone formation capacity of ADSCs and BMSCs in a canine sinus floor augmentation model. In in vitro studies, BMSCs had a higher proliferative ability and greater osteogenic differentiation potential at both the mRNA and protein levels. When GFP-labeled cells on calcium phosphate cement (CPC) scaffolds were implanted subcutaneously into nude mice, both ADSCs and BMSCs survived for 4 wks, but only BMSCs formed new bone. Furthermore, according to sequential fluorescence labeling results for the canine sinus, BMSCs promoted rapid and greater bone regeneration during the entire observation period. In contrast, obvious mineralization was detected starting from 3 wks after implantation in the ADSC group. These results suggest that BMSCs might be more useful than ADSCs for rapid bone regeneration for sinus augmentation with simultaneous implant placement.

Bemisia tabaci (Gennadius) is an important agricultural pest with a worldwide distribution. Although B. tabaci is known to have a unique haplodiploid reproductive strategy, its sex determination mechanism is largely unknown. In this study, we cloned the full-length sequence of B. tabaci doublesex (Btdsx) and found that Btdsx has 28 splicing isoforms. We found two new splicing isoforms of transformer 2 (Bttra2), which encode two proteins. We also confirmed that both genes lack sex-specific splicing isoforms. Real-time quantitative PCR analysis showed that the expression of Btdsx and Bttra2 is higher in males than in females. RNA interference of Bttra2 affected the expression of Btdsx and vice versa. Furthermore, silencing of Bttra2 or Btdsx caused malformation of the male genitalia (anal style). It did not affect the female phenotype, but reduced the expression of vitellogenin gene in females. These results indicate that Btdsx is associated with sex determination in B. tabaci and that Btdsx and Bttra2 affect each other and are important for male genitalia formation. In addition to increasing our understanding of the roles of dsx and tra2 in the sex determination of B. tabaci, the results will be useful for studies of sex determination in other haplodiploid species.